/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.table.typeutils;

import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.api.common.typeutils.TypeSerializerSnapshot;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.DataOutputView;
import org.apache.flink.table.api.dataview.MapView;

import java.io.IOException;
import java.util.Map;

/**
 * A serializer for {@link MapView}. The serializer relies on a key serializer and a value
 * serializer for the serialization of the map's key-value pairs.
 *
 * <p>The serialization format for the map is as follows: four bytes for the length of the map,
 * followed by the serialized representation of each key-value pair. To allow null values,
 * each value is prefixed by a null marker.
 *
 * @param <K> The type of the keys in the map.
 * @param <V> The type of the values in the map.
 */
public class MapViewSerializer<K, V> extends TypeSerializer<MapView<K, V>> {
	private static final long serialVersionUID = 202624224378185203L;

	private final TypeSerializer<Map<K, V>> mapSerializer;

	public MapViewSerializer(TypeSerializer<Map<K, V>> mapSerializer) {
		this.mapSerializer = mapSerializer;
	}

	@Override
	public boolean isImmutableType() {
		return false;
	}

	@Override
	public TypeSerializer<MapView<K, V>> duplicate() {
		return new MapViewSerializer<>(mapSerializer);
	}

	@Override
	public MapView<K, V> createInstance() {
		return new MapView<>();
	}

	@Override
	public MapView<K, V> copy(MapView<K, V> from) {
		return new MapView<>(null, null, mapSerializer.copy(from.map));
	}

	@Override
	public MapView<K, V> copy(MapView<K, V> from, MapView<K, V> reuse) {
		return copy(from);
	}

	@Override
	public int getLength() {
		return -1;
	}

	@Override
	public void serialize(MapView<K, V> record, DataOutputView target) throws IOException {
		mapSerializer.serialize(record.map, target);
	}

	@Override
	public MapView<K, V> deserialize(DataInputView source) throws IOException {
		return new MapView<>(null, null, mapSerializer.deserialize(source));
	}

	@Override
	public MapView<K, V> deserialize(MapView<K, V> reuse, DataInputView source) throws IOException {
		return deserialize(source);
	}

	@Override
	public void copy(DataInputView source, DataOutputView target) throws IOException {
		mapSerializer.copy(source, target);
	}

	@Override
	public boolean equals(Object obj) {
		if (obj instanceof MapViewSerializer) {
			//noinspection unchecked
			MapViewSerializer<K, V> other = (MapViewSerializer<K, V>) obj;
			return mapSerializer.equals(other.mapSerializer);
		}
		return false;
	}

	@Override
	public int hashCode() {
		return mapSerializer.hashCode();
	}

	@Override
	public TypeSerializerSnapshot<MapView<K, V>> snapshotConfiguration() {
		throw new UnsupportedOperationException();
	}
}
